Is a pressurized air object heavier?

Page 1 of 4  
Is a pressurized air object heavier? In other words, is an object heavier when it contains compressed air than when it's empty? For example, if I have a tire and weigh it before pumping it full of air, will it be heavier after it's pumped up? I say NO. A friend of mine insists it will be heavier once it's filled with air. Who is right?
This is one of those fun topics that no one can agree on, and would require a very accurrate scale that would most likely need to measure down to the milligram.
Note: This would be regular compressed air from an air compressor, not helium or another gas, which might make it lighter (even though I highly doubt a tire full of air would float).
Mark
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@UNLISTED.com wrote:

Your friend.
http://www.cashflo.co.uk/Air.html
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

He's talking about compressed AIR...not LIQUID propane... ROFL...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

compressed gas propane. and liquid air is compressed air: so it is the same thing only completely different.
A more appropriate example would be comparing the weigh of a full scuba tank and and empty. Don't need a very sensitive scale for that.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'll just laughing at you. It's all the same thing. The more you put in, the more it weighs.
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Propane is liquid. (LP = Liquid Propane) (Now who is the idiot?) :) Liquid is a big difference from air. However, that website that John posted does prove I am wrong. I just wonder how much weight is added to a 15" tire when 32 lbs of air is added. It can't be a heck of a lot.... I suppose there is a way to figure this from that website, if one was to know how much air went into the tire, but I dont know how much air, and am not good at math. A scale would be easier, but would have to be very accurate.
Mark
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Actually, it's not. A liquid is only a liquid because of temperature and pressure combination. IOW, you can take any gas, compress it enough, and it will become liquid.

You can figure it out if you know the volume of the tire.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Do you mean the 32 pounds of air doesn't weigh 32 pounds? :-) Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
@softhome.net says...

....or does it cost 32. ;-)
--
Keith


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@yahoo.com says...

Not *any* gas. There is no liquid phase of helium at room temperature at any pressure.

0ATM (note: differential pressures). Air is mostly N2 and O2, so it has a weight of, say 30g/mole (O2 is 32g/mole, N2 is 28g/mole). At STP there are 22.4moles/l so that's about 375g/l. So, at 2ATM a tire will weight about 750grams per liter of tire volume more than it will deflated. That doesn't sound like it's going to to take a tremendously accurate scale to measure. ;-)
--
Keith


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
krw wrote:

Actually it is 22.4L/mole at STP; atmospheric pressure would be quite great your way ;) So 1 L of air at 2 atm would weigh about 2.7g.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@gmail.com says...

Damn, sitting thinking about it after, I *knew* I screwed something up. My calculation would have made a 1cu.ft. bucket of 2ATM air weigh upwards of 50 lbs! Oops. Thanks for the catch! <blush>
--
Keith




Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Try again. Density of air at STP is 1.29 grams per liter.
--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Of course there is a diffference between liquids and gases. Liquids run into the streams and gases float. AFAIC gases don't weigh anything. When they talk about air pressure, they're referring to the emotional tension of never knowing where one's next breath will come from.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Of course they weigh something.
Some are denser than air and sink. For example CO2. Remember that village smothered in Africa. That was CO2 rising from a lake then moving along the ground.
Some are lighter than air and rise. Helium is an everyday example.
Some like Nitrogen and Oxygen are about the same as the mixture of gases we call air and just disperse. If you weighed them on an everyday scale the scale would say zero, but they have mass and are attracted to the Earth by gravity.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dan Espen wrote:

Next question:
Will a closed box with a bunch of canaries in it weigh less if the canaries are flying around than if they are walking around on the inside bottom. <G>
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jeff Wisnia wrote:

Even better question, did mm just wake up from a year long nap? LOL
Canary question is interesting. My answer is the box would weigh the same, because gravity is still acting on both the box and the canaries. The upward force against the canaries wings which is keeping the canaries in the air causes an equal an opposite force against the air, which ultimately is transfered through the air and to the bottom of the box, resulting in the force which we call weight.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@optonline.net wrote:

<snipped>
Your correct of course, but the simpler answer is just that the mass of the box and all the stuff inside it stays the same, so its "weight" must too.
Fot thse who don't already know this one, which way does a kid's free floating helium balloon moored on a string inside a schoolbus move when the bus decelerates, and why?
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jeff Wisnia wrote:

Relative to the bus, or to the ground :)
nate
--
replace "fly" with "com" to reply.
http://home.comcast.net/~njnagel
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.